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Old Oct 21, 2006, 08:26 PM
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Quote:
Originally Posted by tic
I don't like this "game" just tell us what you bought and how much less than advertised capacity the pack took.. Please?
I guess searching for my other posts recently is too hard of a game for you.
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Old Oct 21, 2006, 08:30 PM
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Quote:
Originally Posted by HPSOV
1000-1300

How about 1300 mah in at 0.2 amps (with a starting voltage of a hair over 'lipo empty voltage)? And 1000 mah back out (with cut off voltage of 3.4 volts), at 5 amps . . . Note, chosing this cut off voltage results in a 'open voltage reading of the lipo of just a hair over 'lipo -empty'.


I'd say you bought the same batteries I did and performed this test yourself already.

FYI, advertised capacity 1500 mah
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Old Oct 21, 2006, 09:25 PM
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Is this a continuation of your TrueRC rant?
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Old Oct 22, 2006, 12:11 AM
so i rewired it...
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Not all batteries will have the same voltage/mah discharge graph. Try a full charge/discharge.
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Old Oct 22, 2006, 06:49 PM
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Full charge, full discharge ends up with 1300 (and change) capacity. Watt meter used to measure discharge, Ice charger used to measure what goes in.

1300 (and change) when discharged at roughly 10 amps (held voltage very well, I hadn't seen 10 amps out of this choice of motor and prop before). I saw 'fully discharged, when the resting voltage an hour after the test was 10.8 (actually, 10.79, but if you won't tell, I won't)

1300 (and change) when discharged at roughly 5 amps (10.81 after test resting voltage).

1300 (and change) when discharged at 0.2 amps.
[Sorry, but this is a 1300 mah pack, NOT 1500. 1500 is a misrepresentation]

I'll give this battery credit, it did deliver 1300 mah solidly for all of the amp draws I'll really need.

The person(s) who suggested doing a full charge/discharge, instead of relying on partial charge voltage were correct.
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Old Oct 22, 2006, 07:08 PM
tic
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Quote:
Originally Posted by Nethole
I guess searching for my other posts recently is too hard of a game for you.
Sorry, I didn't realize searching for all your posts was part of the game
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Old Oct 22, 2006, 07:13 PM
That's a funny word
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You are using 10.8 as "empty" and 12.6 for "full"

What are the specs on the cells? Will the temp affect the total capacity reading?

Is the point of this thread that you think the pack should've delivered 1500 mah at .2 amps between 12.6 to 10.8?
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Old Oct 22, 2006, 08:55 PM
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Quote:
Originally Posted by gulio
You are using 10.8 as "empty" and 12.6 for "full"

What are the specs on the cells? Will the temp affect the total capacity reading?

Is the point of this thread that you think the pack should've delivered 1500 mah at .2 amps between 12.6 to 10.8?

Instead of questioning my statements, how about making some statements of your own? Such as "I believe a battery with a given mah rating should provide that rating between 12.6 and 10.8 when drained at 0.2 amps" (Or pick what ever numbers you see fit).

You're trying to throw doubt on my statements, yet you're not providing any statements yourself that can be questioned.

Earlier someone suggested posting how the battery faired from 'full' to completely empty. So, I did that. Turns out their suggestion was correct, and I got a very different answer for the capacity of the battery than I did from my 'partial charge' answer. (suprised me). I thought I could perform the tests using partial charge to full, to guarantee I wouldn't accidentally overdrain the battery while testing.


The point of this thread was to find out what was considered acceptable for a pack given a certain advertised rating. I had my beliefs (even a few beliefs on how to measure capacity using partial charge, which were challenged by this thread and proven wrong), but I wanted to find out what was acceptable for a battery to provide given a sellers advertised rating.


I've heard that the mah capacity for cells has been what the cells can give at a particularly small amperage. Often a drain so small, that we would never encounter that small a drain in real life. Some battery venders bring up that 'reasoning' when a cell doesn't provide the advertised mah. But I've tested these particular cells at such a small amperage (0.2 amps), and the capacity from 4.2 volts down to 3.6, and the capacity is much less than what is advertised.


I've heard people state 'some batteries are good', 'such and such battery is bad', but statements like that aren't useful to me.

Statements like 'this battery will provide 1300 mah at 0.2 amps, roughly the same at 5 amps, and suprisingly close to 1300 at 9-10 amps.' That's a useful statement. If I were looking or expecting a 1300 mah battery, I'd be thrilled, especially considering how well it held voltage for the 9-10 amps drain.

If I were expecting a 1500 mah battery, I wouldn't be as thrilled. If I were expecting 95 gr pack, and received a 108 gr pack, I'd be less thrilled.

If you were expecting a 1500 mah 95 gr battery, and received a 1300 mah 108 gr battery, how would you feel?

If you knew that such-and-such battery were ACTUALLY going to provide you with 1300 mah and weight 108 gr, and you knew that from the get go, then when it arrives, you can be content that you got what you were sold.
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Old Oct 22, 2006, 09:10 PM
tic
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Someone's not having a magical day.. I'd be upset also
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Old Oct 22, 2006, 09:58 PM
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That is why there is a Battery Graph Vault here on RC Groups with many test / graph done by independent testers / users. Have a look there and see how the cells / packs compare to the vendors claims.



Charles
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Old Oct 23, 2006, 05:25 AM
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Quote:
Originally Posted by everydayflyer
That is why there is a Battery Graph Vault here on RC Groups with many test / graph done by independent testers / users. Have a look there and see how the cells / packs compare to the vendors claims.



Charles
Yup, the Battery graph Vault is wonder, but these are newly released cells and they're not (yet) in the vault.
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Old Oct 23, 2006, 09:32 AM
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Nethole,
Reference your statement.....
"The point of this thread was to find out what was considered acceptable for a pack given a certain advertised rating."

By looking at the vault data, it is easy to determine what the typical rated capacity versus actual capacity is at low and high draws. I would guess that 99% of the cells tested deliver over 100% of rated capacity at 0.2C discharge and over 90% of capacity at full rated draw.

IMO, typical = acceptable
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Old Oct 23, 2006, 09:48 AM
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Quote:
Originally Posted by hoppy
Nethole,
Reference your statement.....
"The point of this thread was to find out what was considered acceptable for a pack given a certain advertised rating."

By looking at the vault data, it is easy to determine what the typical rated capacity versus actual capacity is at low and high draws. I would guess that 99% of the cells tested deliver over 100% of rated capacity at 0.2C discharge and over 90% of capacity at full rated draw.

IMO, typical = acceptable

If that's the case, then the TRUERC 1500 mah cells are not 'acceptable' . . .
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Old Oct 23, 2006, 12:07 PM
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Not in my book...

Some vendors in fact, under-rate the capacity of their cells so that (IMO) they can deliver the advertised C-rate discharge and deliver close to full advertised rated mah at that level.
I'd rather experience that situation rather than one where the delivered energy is less than advertised. The penalty of course is a heavier cell..

The question now is do you just have a "bad" pack or are they all like that.
TrueRC is the only one who can help you with that question.

The other side of the coin is how were the cells treated after you received them - maybe it was something you did.... not criticizing, just looking at the possible reasons for a poor performing pack. Overdischarge/overcharge/overdraw can all harm a pack.

I see where TrueRC offered to refund the purchase price if you returned them prepaid. The question here is, if I keep them, will they give me 200-300 cycles at the discharge level I plan to use them at or is the lower initial mah delivery indicative of a faulty pack that will soon fail. That question cannot be answered...soooooo, it's decision time. Do I roll the dice on how long they will last or spend the bucks to send them back.

I'd send it back and move on.
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Old Oct 23, 2006, 12:32 PM
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Hoppy......"Overdischarge/overcharge/overdraw" .....
I think it's abbreviation time to help people remember.... OD/OC/OD
As in, "Hey man, did you OD your pack?"

rc
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